Shelf unit



FIG. 1 is a front perspective view of a shelf unit showing my new design;

FIG. 2 is a rear perspective view of the shelf unit of FIG. 1;

FIG. 3 is a front elevational view of the shelf unit of FIG. 1; and

FIG. 4 is a front perspective view showing a second embodiment of the shelf unit shown in FIG. 1. 

The ornamental design for a shelf unit, as shown and described. 